Grasslands

Grasslands are ecosystems composed primarily of herbaceous plant species dominated by grasses. On the Willowsford landscape, the majority of our grasslands are remnants from agricultural activity. While the historic land cover of northern Virginia was mostly forest, grasslands play an important role in biodiversity. Many plant and animal species require grasslands to survive. Grasslands are prime targets for development and agriculture and are thus vulnerable to habitat loss. As open grassland is lost, grassland obligate species, those that require grasslands to survive, go homeless and hungry. Willowsford Conservancy is committed to preserving and improving grassland habitat across our landscape.

Benefits of grasslands

Besides being beautiful, grasslands provide many benefits such as wildlife habitat, carbon sequestration, and ecosystem diversity to name just a few!

WILDLIFE HABITAT

Grassland Birds

Many grassland bird species are experiencing population declines throughout North America. Habitat loss and fragmentation is presumed to be the primary culprit for the reduction in these species.

Certain grassland birds are ground-nesting, meaning they make their nests in aboveground vegetation in open grassland areas. During nesting season in the spring and summer, many of these nests are vulnerable to disturbance or destruction from mowing activity.

Grassland insects provide the foundation for many bird populations, even those that do not nest in grasslands. For example, the eastern bluebird is a cavity-nester who builds nests in dead trees in the forest. However, they are considered a grassland bird because they rely on grassland insects as a food source.

Mammals (and more birds)

Mammals such as rabbits, voles, and deer as well as large birds such as quail and turkey also use grasslands to nest and raise young.

Smaller animals like rabbits and voles can utilize short grasses for habitat. However, larger animals such as turkey and deer require taller grasses to provide cover from predators.

Pollinators

Pollinators encompass a broad spectrum of wildlife such as butterflies, moths, bees, hummingbirds, and even bats! Many native flowering plants rely on pollinators to transfer pollen to reproduce.

Beneficial plants for pollinators can be split into two groups:

Food resources – Nectar and pollen from wildflowers provide sugars and protein for a variety of butterflies, moths, bees, and hummingbirds.

Host plants – Host plants are species which certain insects require for reproduction. For example, monarch butterfly caterpillars can only eat milkweed leaves. Adult monarchs lay eggs on milkweed (their host plant) so when the hungry caterpillars hatch they can start eating right away!

Raptors

Birds of prey, or raptors, are carnivorous birds which boast hooked beaks, strong talons, and keen eyesight. Raptors encompass a broad group of birds including eagles, hawks, falcons, owls, and vultures.

Raptors favor forest edge habitat, or the border between grasslands and forests. They will nest in the woods and look for prey in grasslands. Solitary trees, telephone poles, and fence posts provide perches with a clear view for raptors to spot prey.

The unique matrix of forests and grasslands at Willowsford provide good habitat for many raptor species.

CARBON SEQUESTRATION

When discussing carbon sequestration, conversations typically drift towards forests, however grasslands play a major role in the Earth’s carbon cycle. Annual growth, death, and decay of plants store a substantial amount of carbon in the soil through roots and surface organic matter.

Many native grassland plant species such as switchgrass and bluestem have deep rooting systems which increase the amount of carbon sequestered in the soil as opposed to non-native turfgrasses such as Kentucky bluegrass and bermudagrass.

ECOSYSTEM DIVERSITY

Forests are historically the most common ecosystem across the Virginia Piedmont landscape. However, much of the grassland habitat in the Midwest has been lost through development and agricultural expansion. Thus, providing refuge for wildlife requiring grassland habitat is important for species such as the Henslow’s sparrow.

Henslow’s sparrow’s population is in steep decline and is considered a threatened species in Virginia. Grassland habitat in the eastern United States has helped slow the decline of the Henslow’s sparrow as well as many other grassland bird species.

Native Plants

Native grassland plant species have evolved with wildlife for thousands of years. As such, native species provide many habitat benefits which non-native species do not.

For example, most native grass species in Virginia are bunch grasses meaning they grow in clumps whereas most non-native grasses used in lawns are sod-forming. Bunch grasses provide space underneath the upper grass “canopy” allowing movement and nesting space for wildlife. However, sod-forming grasses create low, dense mats of vegetation which reduce nesting space and restrict movement.

Native wildflowers in grassland ecosystems provide food sources to pollinators, increase plant diversity, and create beautiful landscapes. Pollinators benefit from nectar and pollen from flowering plants while caterpillars and other insects eat leaves. Birds and mammals will feed on the fruits and seeds provided by successfully reproducing flowering plants.

Most native wildflowers cannot survive frequent mowing. By cutting flower heads before they can bloom and set seed, they cannot reproduce. Part of the Conservancy’s Grassland Management Program designates certain areas as Designated Wildlife Habitat where we promote the growth and reproduction of wildflowers.

Grassland Residents

Monarch Butterfly

Monarch butterflies, as their name implies, are one of the most majestic butterflies in North America. Their rich orange and black pattern give them an ominous beauty because while we find them attractive, predators take their coloration as a warning. Monarch butterflies are toxic to most predators which they develop as caterpillars. Monarch caterpillars feed on milkweed plants and incorporate the milkweed’s toxic secretions into their own bodies!

The monarch butterfly is a good example of the importance of preserving grassland ecosystems throughout the United States. They are one of the few migratory insects in North America and travel from Canada all the way to Mexico. It actually takes multiple generations of monarchs to make one trip!

Since monarchs require milkweed to reproduce, if they cannot find milkweed along their route, they cannot produce offspring to continue their journey. Widespread grassland habitat loss is a contributing factor to the monarch’s population decline. However, preserving grasslands provides monarchs with “waystations” along their migratory routes.

According to the National Wildlife Federation, it is estimated that since the 1990s the monarch population has declined by roughly 90%. This decline is in large part due to habitat loss through their migratory route in the United States as well as forest fragmentation of their overwintering habitat in Mexico. Ongoing efforts to increase the distribution of milkweed and healthy grassland habitat is underway to help protect monarch butterflies from disappearing. These efforts benefit hundreds of other pollinator and grassland species as well!

Eastern Meadowlark

Eastern meadowlarks are year-round Virginia residents and build their nests in grassland underbrush. They tend to be shy and can be startling when they burst from the undergrowth only feet away from you.

Meadowlarks typically require at least 5 acres of contiguous grassland area in order to establish a territory and build nests. Due to their inconspicuous behavior and building nests at ground level, meadowlarks are susceptible to nestling mortality due to mowing. By postponing mowing until after the nesting season, we can support meadowlark populations in our grassland habitat. Meadowlarks can return to the same nesting territory over the course of their lifetime as long as their nests are not disturbed.

Eastern Meadowlark populations in Virginia have declined similar to populations throughout the United States and are considered a species of conservation need by the Virginia Department of Game and Inland Fisheries.

American Kestrel

The American kestrel is North America’s smallest falcon, but don’t let its size fool you. It’s a fierce predator and can often be seen on poles and powerlines clutching their most recent takeout meal. Kestrels are found in grassland habitats where they hunt prey ranging from insects to small mammals and songbirds.

American kestrels are cavity nesting birds, meaning they build their nests in tree cavities, rock crevices, and manmade structures, typically in or along the edges of grasslands. They cannot make their own cavities in trees and thus rely on abandoned woodpecker nests or natural tree hollows and standing dead trees.

Because American kestrels are cavity nesters they will readily take to nest boxes. Many nest box programs in the United States, including in Virginia, have helped support kestrel populations.

Grassland Management

Active grassland management at Willowsford primarily involves bush hogging; using a large tractor-pulled brush mower. The purpose of bush hogging is to maintain open grasslands by preventing the establishment of woody species which over time can take over the area. In certain locations, we want this natural succession from grassland to woodland to occur. However, in other areas we want to maintain grassland habitat for wildlife, landscape diversity, and for aesthetics.

For wildlife which relies on grassland habitat, early bush hogging and mowing can have detrimental effects. Grassland birds, deer, rabbits, and other species use grasslands for nesting in the spring and summer. Willowsford Conservancy delays bush hogging to allow wildlife to successfully nest and reproduce, thereby supporting our local wildlife population. Additionally, delaying bush hogging and mowing allows wildflowers to bloom and set seed, increasing pollinator resources and the beauty of our landscape.

The Conservancy elects certain areas as Designated Wildlife Habitat which are grassland areas of high wildlife value. These areas possess a variety of beneficial characteristics such as pollinator resources, forage such as seed, berries, and foliage, and good vegetative coverage. Designated Wildlife Habitat areas are bush hogged once a year in the fall to allow wildlife, pollinator, and floral reproduction to take place and provide cover throughout the year. Bush hogging once a year not only improves grassland habitat value but also reduces fossil fuel usage.

NATURALIZATION AREAS

Naturalization Areas are grasslands which the Conservancy has elected to not bush hog unless deemed necessary. The Conservancy wishes to allow natural succession to take place and allow these grassland areas to convert to forested areas over time. Allowing these areas to convert to woodland reduces forest fragmentation which has important implications for wildlife. Certain woodland species require larger patches of forest such as bobcats, bears, and many species of songbirds and owls. Having larger contiguous habitat areas also reduces human/wildlife conflict by allowing animals to travel without crossing developed areas. Additionally, eliminating bush hogging disturbance will allow more wildlife to occupy these Naturalization Areas.

Suggested Wildlife Viewing Areas

WET MEADOW

The Grange: The Wet Meadow is the Conservancy’s flagship grassland ecosystem where we manage a diversity of native wildflower and grass species. Pollinators can be seen collecting nectar and pollen while birds dart through the air trying to catch a meal on the wing. Additionally, vernal pools in the Wet Meadow provide the opportunity to observe dragonflies and amphibians.

FARM LOOP TRAIL

The Grange: The eastern Farm Loop Trail boasts 10 bluebird nest boxes which are typically occupied by either eastern bluebirds or tree swallows. Other potential species which could be observed are Carolina chickadees, house wrens, and tufted titmice.

WILLOW GROVE COMMUNITY PARK

The Grove: With the Corn Crib situated in the middle of an open field overlooking Willow Grove Pond, the Willow Grove Community Park is an idyllic setting to observe grassland wildlife.

BULL RUN OVERLOOK TRAIL

The Greens: The Bull Run Overlook Trail crosses through some of the largest and least disturbed grasslands in Willowsford. The seasonal wildflower color palette provides a wonderful backdrop for observing raptors soaring through the air or perched, intently searching for their next meal.